Is there one anywhere that shows what will happen if you're in a crash, with the shoulder belt placed behind your back? Or an article? Is it essentially the same as a lap belt or worse? My 9.5 yr old nephew (and sil and the other nephew) is visiting for the weekend and I made him do it right in my car, but he said he always puts it behind his back because it's uncomfortable. He's around 100 lbs. I think he passes the 5 step test other than the way the shoulder belt fits, and in some cars, he'd pass in that area. He was riding in the 3rd row of my minivan and it was a bit too high on him.